Module documentation for 0.2.6.0

th-abstraction

This package provides a consistent interface to a subset of Template Haskell.

Currently the package provides a consistent view of the reified declaration
information about datatypes, newtypes, and data family instances. These
interfaces abstract away the differences in the normal and GADT syntax used to
define these types.

Contact Information

Please contact me via GitHub or on the #haskell IRC channel on irc.freenode.net

Changes

Revision history for th-abstraction

0.2.8.0 – 2018-06-29

GADT reification is now much more robust with respect to PolyKinds:

A bug in which universally quantified kind variables were mistakenly
flagged as existential has been fixed.

A bug in which the kinds of existentially quantified type variables
were not substituted properly has been fixed.

More kind equalities are detected than before. For example, in the
following data type:

data T (a :: k) where
MkT :: forall (a :: Bool). T a

We now catch the k ~ Bool equality.

Tweak resolveTypeSynonyms so that failing to reify a type constructor
name so longer results in an error. Among other benefits, this makes
it possible to pass data types with GADT syntax to normalizeDec.

0.2.7.0 – 2018-06-17

Fix bug in which data family instances with duplicate occurrences of type
variables in the left-hand side would have redundant equality constraints
in their contexts.

0.2.6.0 – 2017-09-04

Fix bug in which applySubstitution and freeVariables would ignore
type variables in the kinds of type variable binders.

0.2.5.0

Added pragLineDCompat, newtypeDCompat and tySynInstDCompat

0.2.4.0 – 2017-07-31

Fix bug that caused GADT equality constraints to be incorrect in some cases.

Expose Unpackedness and Strictness (which were unexported by accident).

0.2.3.0 – 2017-06-26

Add resolvePredSynonyms

Add reifyConstructor, which allows reification of ConstructorInfo from
a constructor name, and lookupByConstructorName, which allows directly
looking up a ConstructorInfo from a DatatypeInfo value for a given
constructor Name.

Augment reifyDatatype to be able to look up DatatypeInfo from the Name
of a record selector for one of its constructors. Also add reifyRecord for
reification of of ConstructorInfo from a record name, and
lookupByRecordName, which allows directly looking up a ConstructorInfo
from a DatatypeInfo value for a given record Name.

Fix bug that caused th-abstraction to fail on GHC 7.0 and 7.2 when passing
a vanilla constructor name to reifyDatatype

Make normalizeDec and normalizeCon more robust with respect to
data family instances on GHC 7.6 and 7.8

0.2.2.0 – 2017-06-10

Fix freeVariables on lists not not produce duplicates.

0.2.1.0 – 2017-06-09

Add sensible reify defaults and error messages when we
can’t backport fixes to old GHC Template Haskell output
due to hand-written Decs being processed.